Looks like seventeen parts to me. Even apart from the compositional brilliance, kudos once again to the musicians for memorizing this one.

Notice the unusual metric groupings. The parts I've labeled as "intro chords - link" are single measure alternations between the tonic and the relative minor chords, but the verse begins on what originally sounds like measure four of the link, on the relative minor chord.

Thus, the verse is off-kilter. And it doesn't resolve; at measure nine, a new melody asserts itself as though we are in a strong measure, but it doesn't feel like we are.

At nine bars, the bridge is also irregular, modulating to the parallel minor and progressing through a beautiful cycle of fourths back, as ever it seems, to that chorus.